1. Field of the Invention
The invention relates to a vehicular air conditioning system and air conditioning method. More particularly, the invention relates to a vehicular air conditioning system and air conditioning method provided with a pre-air conditioning function which air conditions a vehicle cabin before an occupant gets into the vehicle.
2. Description of the Related Art
In recent years, various technologies have been proposed to perform so-called pre-air conditioning which air conditions a vehicle cabin before an occupant gets into the vehicle according to a command by an occupant using remote control, for example, or a timer setting or the like.
For example, the technology disclosed in Japanese Patent Application Publication No. JP-A-2003-237358 performs pre-air conditioning by blowing cold air that was cooled by a cooling unit to a temperature lower than the temperature inside the vehicle cabin from an air outlet at a low rate at which the cooled air does not mix with the air in the vehicle cabin. As a result, the cold air gradually accumulates at a low level in the vehicle cabin from above a front seat, which is in a lower portion in the vehicle cabin, due to both the fact that the specific gravity of the cold air is greater than that of the air in the vehicle cabin because its temperature is lower than that of the air inside the vehicle cabin, and the fact that the cold air is blown at a rate at which it does not mix with the air in the vehicle cabin. Accordingly, an uncomfortable sensation is not imparted on the occupant when the occupant gets into the vehicle again. Further, a blower fan is driven to produce extremely little airflow, which enables energy consumption to be reduced.
The problem with the technology disclosed in Japanese Patent Application Publication No. JP-A-2003-237358, however, is that it only accumulates cold air at a low level inside the vehicle cabin, so when the occupant gets into the vehicle, the temperature of the air around the upper body of the occupant is still warm. Thus, that technology is unable to give the occupant a comfortable sensation.